In 2006, a judge vacated the conviction of Cy Greene, who had spent more than 22 years in prison for a 1983 murder in Brooklyn. Greene had produced evidence suggesting that prosecutors had hidden information pointing to his innocence.

Greene sued the Brooklyn District Attorney's Office and the NYPD for $22.5 million. On Tuesday, a Brooklyn judge ruled that former Brooklyn District Attorney Charles Hynes must testify under oath in the case, even though the prosecution took place before he took office.

A witness, who claimed to have seen three men running from the station, identified them as a crew of pickpockets he knew. Greene was not among those three suspects. It was one of those suspects who implicated Greene, claiming Greene had done the stabbing. Greene is 5'2".

Greene was sentenced to 15-years-to-life in prison. He appealed his case. In 2003, his lawyer discovered that prosecutors had withheld evidence from the defense.

Jae Hark Kim, who was with Choi during the crime, told police that a a group of men had mugged them and that the man with the knife was around six feet tall. In his statement for the D.A.'s office he described the stabber as "the tall guy." But prosecutors erased the "tall guy" reference in Kim's statement, and Kim identified Greene at trial.

Prosecutors did not turn over information showing that witnesses (including a cab driver) claimed that the men they saw fleeing the scene spoke Spanish. Greene speaks only English.

And prosecutors also did not reveal that police had initially arrested another man, Leonard Best, who had been identified by a witness. The man, however, escaped from custody and was never found. Best's brother, Mark, later claimed that Leonard committed the stabbing.

Elizabeth Holtzman was Brooklyn's D.A. during Greene's trial. But, Greene argues in his suit, the suppression of evidence continued under Hynes's watch. Hynes, who took office in 1990, is listed as a defendant.

While Hynes may not be able to speak specifically about the case against Greene, he is able to offer knowledge about how prosecutors are disciplined for misconduct, concluded Brooklyn Magistrate Cheryl Pollak.

A similar line of reasoning forced former Brooklyn detective Louis Scarcella to testify in Jabbar Collins's wrongful conviction suit. Scarcella was not involved in the case, but the judge ruled that Scarcella could offer information about police practices and misconduct in the 1990s. The Brooklyn D.A.'s office has been reviewing every conviction involving Scarcella because of allegations of serial misconduct.

Hynes had to testify in Collins's case as well. under oath, he admitted for the first time that he believed that Collins was probably innocent. Last week, the state agreed to pay Collins $3 million for his 15-year imprisonment.